1. Field of the Invention
The present invention generally relates to a method of and a device for controlling switches with regard to affiliation of remote line-collection devices, and particularly relates to a method of and a device for controlling switches with regard to affiliation of remote line-collection devices when the affiliation of remote line-collection devices is changed from a switch to switch.
In recent years, there have been increasing competitions in rendering telephone services between different carriers. An increase in the competitions demands a cost reduction and simpler networks that are easier to be maintained. This is achieved by simplifying network configurations of station switches, which have become exceedingly complex due to use of mobile-communication networks, digital communication networks, etc., in addition to use of general telephone network. To this end, integration of host stations has been underway with an aim of achieving a simplified network, in which large-capacity station switches would be used as a core for affiliated remote line-collection devices.
2. Description of the Related Art
Remote line-collection devices are not provided with a switching function, and are only equipped with a function to multiplex and demultiplex communication lines. Such remote line-collection devices are conventionally installed in remote locations away from switches, and are controlled by the switches. This configuration is typically used in order to enhance efficient use of resources by installing remote line-collection devices in areas where fewer subscribers are located and by connecting the remote line-collection devices with switches situated at remote positions.
FIG. 1 is an illustrative drawing showing a network configuration for controlling affiliation of remote line-collection devices in the related art. In FIG. 1, switches 1 through n together form a network, and are monitored by a centralized maintenance center 10. In normal operations, remote line-collection devices RLC(A) through RLC(C) are affiliated with (belong to) the switch 1, and have the switch n as a backup switch to be affiliated with. Remote line-collection devices RLC(D) and RLC(E) are affiliated with the switch 2 in normal operations, and the switch 1 serves as a backup switch for these remote line-collection devices. Further, remote line-collection devices RLC(F) and RLC(G) belong to (are affiliated with) the switch n, and have the switch 2 as a backup switch.
In the network comprised of the switches 1 through n, the remote line-collection devices RLC(A) through RLC(C) are affiliated not only with the switch 1 but also with the switch n. When a transmission line suffers malfunction, a switch has to be made from the current transmission line to a backup transmission line, and, thus, RLC data of all the remote line-collection devices needs to be provided in duplicate. Because of this, the switch n has not only RLC data DRLC(F) and DRLC(G) (i.e., data of the remote line-collection devices RLC(F) and RLC(G)) but also RLC data DRLC(A) and DRLC(C) (i.e., data of the remote line-collection devices RLC(A) through RLC(C)). Here, the RLC data refers to control data that is necessary for controlling a remote line-collection device from a affiliated switch.
In this manner, the switch n, which does not control the remote line-collection devices RLC(A) through RLC(C) during normal operations, needs to have a RLC-data-storage area that has the same capacity as that of the switch 1. The need for such an excessive memory space leads to a cost increase.
Further, when RLC data DRLC(A) of the remote line-collection device RLC(A) is modified in the switch 1, for example, the same data modification needs to be made in the switch n despite the fact that the switch n does not control the remote line-collection device RLC(A) during normal operations. Such modification has a huge impact on processing capacities of the switches 1 and n and traffic between the switches 1 and n. RLC-data modification during a high traffic period of a daytime, which affects call processing seriously, may trigger a system shutdown by exceeding a limit that the system can handle.
In consideration of such a risk, RLC-data modification tends to be carried out during a nighttime when traffic is low. This creates concerns about convenience and safety of maintenance work, and results in a cost increase because of a need for higher wages for nighttime maintenance workers.
Accordingly, there is a need for such a method of and a device for controlling switches with regard to affiliation of remote line-collection devices that a control-data-storage area can be reduced in size and an increase in traffic caused by modification of control data can be reduced.
Accordingly, it is a general object of the present invention to provide a method of and a device for controlling switches which can satisfy the need described above.
It is another and more specific object of the present invention to provide such a method of and a device for controlling switches with regard to affiliation of remote line-collection devices that a control-data-storage area can be reduced in size and an increase in traffic caused by modification of control data can be reduced.
In order to achieve the above objects according to the present invention, a method of controlling affiliation of a remote line-collection device with a plurality of switches connected via a network includes the steps of providing each switch with a backup-storage area in advance in addition to a normal storage area, and transferring control data of the remote line-collection device from the normal storage area of a first switch to the backup-storage area of a second switch when affiliation of the remote line-collection device is changed from the first switch to the second switch.
In the method described above, each switch stores control data of remote line-collection devices that belong thereto in the normal storage area during normal operations, and does not have the control data of the remote line-collection device stored therein despite the fact that this remote line-collection device will be affiliated therewith when a backup switch is necessary. Because of this configuration, control data of a given remote line-collection device is modified without seriously affecting traffic of data. Further, since the backup area of a given switch needs to have only the smallest necessary space for storing control data of remote line-collection devices that may use the given switch as a backup switch, a total size of the memory space for storing control data can be significantly reduced in comparison with a size of a memory space required in the related art.
Other objects and further features of the present invention will be apparent from the following detailed description when read in conjunction with the accompanying drawings.